Fluoropolymers have good properties, including heat resistance and chemical resistance, owing to the fluorine atoms therein. Thus, they are used in a wide variety of fields and developed into various applications in accordance with factors such as the compositions and structures of fluoropolymers.
Patent Literature 1 discloses one method of producing such fluoropolymers comprising providing a polymer by polymerizing a vinylidene fluoride monomer in an aqueous medium using, as a polymerization initiator, an organic peroxide composition consisting of 10 to 80% by weight of a specific peroxydicarbonate and 20 to 90% by weight of methanol.
Patent Literature 2 discloses one method of producing a tetrafluoroethylene-hexafluoropropylene copolymer comprising the steps of: (1) polymerizing tetrafluoroethylene and hexafluoropropylene in an aqueous medium in the presence of diisopropyl peroxydicarbonate; and (2) fluorinating the tetrafluoroethylene-hexafluoropropylene copolymer produced in the step (1). Patent Literature 3 discloses another method of producing a fluoropolymer comprising polymerizing a fluoromonomer in an aqueous medium in the presence of an oil-soluble peroxide and a hydrocarbon emulsifier.
Further, manufacturers have produced fluororesin which is a copolymer comprising, as copolymerizable units, tetrafluoroethylene, vinylidene fluoride, and an ethylenic unsaturated monomer (other than tetrafluoroethylene and vinylidene fluoride) and which has a storage elastic modulus at 170° C. of 60 to 400 MPa measured by dynamic viscoelasticity measurement (see Patent Literature 4).